The present invention relates to a transmission assembly. More particularly, the present invention relates to a transmission assembly of a vehicle.
A conventional transmission system of a vehicle has a pressing plate to press a transmission chain. After a long period of usage, the pressing plate will not work very well so that the transmission chain will be damaged.
An object of the present invention is to provide a transmission assembly which has an idle wheel to adjust a tightening degree of a transmission chain.
Accordingly, a transmission assembly comprises a frame, a transmission gear disposed on the frame, a driven gear disposed on the frame, and a transmission chain surrounding the transmission gear and the driven gear. The frame has a through hole. A torsion spring has a first end and a second end. A shaft rod has an annular recess. A swing arm has a round hole, a circular hole, and a through aperture. A pivot rod has an annular groove. The shaft rod is inserted in the round hole of the swing arm. The shaft rod passes through the torsion spring and the through hole of the frame. A first C-shaped retainer encloses the annular recess of the shaft rod. An idle wheel engages with the transmission chain. A Bearing is adjacent to the idle wheel. The pivot rod is inserted in the circular hole of the swing arm. The pivot rod passes through the Bearing and the idle wheel. A second C-shaped retainer encloses the annular groove of the pivot rod. The first end of the torsion spring is inserted in the through aperture of the swing arm. The second end of the torsion spring is hooked on the frame. The torsion spring forces the swing arm and the idle wheel to move and vibrate upward. When the transmission chain is tight, the degree of vibration of the swing arm is small and the degree of vibration of the idle wheel is small also. When the transmission chain is loosened, the degree of vibration of the swing arm is large and the degree of vibration of the idle wheel is large also. Therefore, the idle wheel will adjust a tightening degree of the transmission chain.